Fair open access journals

Mathematical Optimization

• Journal of Nonsmooth Analysis and Optimization (JNSAO) - https://jnsao.episciences.org
• Open Journal of Mathematical Optimization (OJMO) - https://ojmo.centre-mersenne.org/

Graph theory, algorithms

• Advances in Combinatorics - https://advances-in-combinatorics.scholasticahq.com/
• DMTCS - https://dmtcs.episciences.org/
• Electronic journal of Combinatorics -https://www.combinatorics.org
• TheoretiCS - https://theoretics.episciences.org/
• Theory of Computing - https://theoryofcomputing.org/
• Innovations in Graph Theory - https://igt.centre-mersenne.org/

Artificial Inteligence

• JAIR - https://www.jair.org/index.php/jair/about
• Journal of Machine Learning Research (JMLR) - https://www.jmlr.org/
• Transactions on Machine Learning Research (TMLR) - https://www.jmlr.org/tmlr/

And many conferences at LIPICs and OpenProceedings.org

See also: https://freejournals.org/current-member-journals/